Cape Town - The Lions will reportedly contest a move which resulted in Springbok lock Franco Mostert signing for Gloucester.
On Wednesday, the English club confirmed that Mostert and tighthead Ruan Dreyer will join former Lions coach Johan Ackermann's charges.
According to Sowetan website, the Lions CEO Rudolf Straeuli said the union will fight to hold onto the Springbok duo.
Ackermann has now convinced son Ruan, flank Jaco Kriel, Mostert and Dreyer, as well as Sharks hooker Franco Marais, to leave South African shores and head to England.
READ: Departing SA coaches give SA Rugby grey hairs
However, it seems like Straeuli has had enough, telling the Sowetan that they will dispute the transfer.
"We are contesting it because it is a transgression of World Rugby's player movement regulations‚" said Straeuli.
"I can't go into specifics of how we are fighting this but the process is under way. Our lawyers are busy with it. This is a legal dispute."
According to Gloucester Live, Ackermann's club is "confident" that there are no issues surrounding the signing of Mostert.
Dreyer has spent his club career to date as part of the Lions organisation, playing for the Golden Lions in the Currie Cup and the Lions in Super Rugby.
Mostert began his career with the Blue Bulls in Pretoria, before switching to Johannesburg with the Lions and also represented the Ricoh Black Rams in the Japanese Top League, before he returned to Super Rugby with the Lions.